Early detection of a variety of pathologies has been shown to dramatically improve the therapeutic outcome for such pathologies. This is particularly true with cancer, and specifically with cancer of the cervix. In the case of cancer of the cervix and other cervix anomalies, the pap smear test has been used for many years as a screening method for the detection of pre-cancerous conditions as well as for the detection of cancer. Unfortunately, this method suffers from excessive errors and results in too many false positive as well as false negative determinations, which increases the overall cost to the health care system. The method requires the physician to scrape cells from the surface of the cervix and transfer the cells to a laboratory where a cytopathologist examines them under a microscope. Statistics on the false positive readings of pap smears range as high as 30% and false negative error rate of 20% to 30% associated with insufficient cell readings or inexpert readings of pap smears are normal as well.
In the case of false negative determinations, additional colposcopic examinations and biopsies of the cervix are carried out on patients with normal tissue, overloading the health care system unnecessarily. On the other hand, false negative pap smears allow the pathologies to evolve to full cancers that could have been treated earlier at much lower costs and with better outcomes.
Fluorescence spectroscopy, which is capable of distinguishing histologically normal and histologically abnormal tissue, has been used for the detection of cervical neoplasia by comparing fluorescence of a suspicious area of the cervix with normal tissue. Since the location of abnormal tissue is often difficult to determine by eye, this approach tends to require highly trained practitioners to determine normal tissue.
In other tissues types, pre-cancerous conditions present themselves in ways that make identification of potential abnormal sites over normal sites much easier than in the cervix. In the colon, for example, the presentation of polyps forming on the interior wall is an indication of possible malignant growth. Spectroscopic studies comparing tissue responses of polyp regions from non-polyp regions show a high degree of difference in the optical signatures of the tissue. This is to be expected, considering the morphologic differences in the tissues. In the cervix, however, surface changes caused by the presence of lesions are often difficult, if not impossible, to see. This indicates that the tissue differences between normal and abnormal tissue are often very subtle, and optical techniques must attempt to distinguish these subtle features.
The tissue fluorescence may be excited, for example, by excitation with UV light. Other spectroscopic methods employ multiple fluorescence excitation wavelengths and use discrimination functions, which frequently cannot easily classify the health of the tissue, even when comparing spectra from the same cervix. Accordingly, these spectroscopic methods have little predictive power when used with other cervixes since each “standard” (normal tissue) invariably may have to be determined for each cervix screened.
It would therefore be desirable to provide a screening system and method that provide an immediate indication of the health of the cervical tissue and could replace a pap smear test as a screening modality, is simpler to perform, does not depend on the specific cervix screened, and can be administered by personnel having minimal medical training.